Disclosed herein is an ink composition comprising a metal salt amine complex; wherein the metal salt amine complex is formed from a metal salt and an amine; a compound selected from the group consisting of a stable free radical, a photoacid generator, and a thermal acid generator; and an optional solvent. Also disclosed is a process including forming a metal salt amine complex; and adding a compound selected from the group consisting of a stable free radical, a photoacid generator, and a thermal acid generator; to the metal salt amine complex to form an ink. Also disclosed is a process including providing an ink composition comprising a metal salt amine complex, wherein the metal salt amine complex is formed from a metal salt and an amine; a compound selected from the group consisting of a stable free radical, a photoacid generator, and a thermal acid generator; and an optional solvent; depositing the ink composition onto a substrate to form deposited features; and treating the deposited features on the substrate to form conductive features on the substrate.
Conductive inks are desired for fabricating conductive patterns for electronic device applications.
There are currently three broad methods for printing conductive patterns. One method is to print metallic flakes. A second method is to prepared stabilized nanoparticles of the metal and subsequently print them followed by sintering. This method allows sintering at much lower temperatures than the bulk metal would require. A third method is to print metallic complexes that are then converted to the metal on the image substrate or object by chemical means.
Printable electronics inks typically use one of these methods, for example printing silver flakes, printing silver nanoparticles, or using silver complexes as the conductive element or conductive precursor prior to printing. For each of these ink categories, there can be drawbacks in ink stability, ease of preparation, and post printing requirements. Metallic flakes can be difficult to print via ink jet printing. Nanoparticle inks can be difficult to prepare and keep stable. Even small increases in the size of the nanoparticles, for example, from 5 nanometers to 10 nanometers in average particle diameter, can result in a 30° C. change in sintering temperatures. Metal complex precursors offer flexibility in terms of printing latitude, but can be difficult to prepare and handle, and can be cost prohibitive.
Solution processable conducting materials, including silver nanoparticle inks, play an important role in electronic device integrations. Conductive inks that can be easily dispersed in suitable solvents and used to fabricate various conducting features in electronic devices such as electrodes and electrical interconnectors by low-cost solution deposition and patterning techniques including spin coating, dip coating, aerosol printing, and ink jet printing technologies are particularly desired.
Xerox® Corporation has invented a nanosilver particle which is stabilized by an organoamine U.S. Pat. No. 8,765,025, which is hereby incorporated by reference herein in its entirety, describes a metal nanoparticle composition that includes an organic-stabilized metal nanoparticle and a solvent in which the solvent selected has the following Hansen solubility parameters: a dispersion parameter of about 16 MPa0.5, or more, and a sum of a polarity parameter and a hydrogen bonding parameter of about 8.0 MPa0.5 or less. U.S. Pat. No. 7,270,694, which is hereby incorporated by reference herein in its entirety, describes a process for preparing stabilized silver nanoparticles comprising reacting a silver compound with a reducing agent comprising a hydrazine compound by incrementally adding the silver compound to a first mixture comprising the reducing agent, a stabilizer comprising an organoamine, and a solvent.
U.S. patent application Ser. No. 13/866,704, which is hereby incorporated by reference herein in its entirety, describes stabilized metal-containing nanoparticles prepared by a first method comprising reacting a silver compound with a reducing agent comprising a hydrazine compound by incrementally adding the silver compound to a first mixture comprising the reducing agent, a stabilizer comprising an organoamine, and a solvent. U.S. patent application Ser. No. 14/188,284, which is hereby incorporated by reference herein in its entirety, describes conductive inks having a high silver content for gravure and flexographic printing and methods for producing such conductive inks.
U.S. patent application Ser. No. 15/061,618, which is hereby incorporated by reference herein in its entirety, describes in the Abstract thereof an ink composition including a metal nanoparticle; at least one aromatic hydrocarbon solvent, wherein the at least one aromatic hydrocarbon solvent is compatible with the metal nanoparticles; at least one aliphatic hydrocarbon solvent, wherein the at least one aliphatic hydrocarbon solvent is compatible with the metal nanoparticles; wherein the ink composition has a metal content of greater than about 45 percent by weight, based upon the total weight of the ink composition; wherein the ink composition has a viscosity of from about 5 to about 30 centipoise at a temperature of about 20 to about 30° C. A process for preparing the ink composition. A process for printing the ink composition comprising pneumatic aerosol printing.
U.S. patent application Ser. No. 14/630,899, which is hereby incorporated by reference herein in its entirety, describes in the Abstract thereof a process including selecting a printing system; selecting an ink composition having ink properties that match the printing system; depositing the ink composition onto a substrate to form an image, to form deposited features, or a combination thereof; optionally, heating the deposited features to form conductive features on the substrate; and performing a post-printing treatment after depositing the ink composition.
U.S. patent application Ser. No. 14/594,746, which is hereby incorporated by reference herein in its entirety, describes in the Abstract thereof a nanosilver ink composition including silver nanoparticles; polystyrene; and an ink vehicle. A process for preparing a nanosilver ink composition comprising combining silver nanoparticles; polystyrene; and an ink vehicle. A process for forming conductive features on a substrate using flexographic and gravure printing processes comprising providing a nanosilver ink composition comprising silver nanoparticles; polystyrene; and an ink vehicle; depositing the nanosilver ink composition onto a substrate to form deposited features; and heating the deposited features on the substrate to form conductive features on the substrate.
U.S. patent application Ser. No. 15/339,399, which is hereby incorporated by reference herein in its entirety, describes in the Abstract thereof an ink composition including a metal nanoparticle; a viscous heat decomposable liquid, wherein the viscous heat decomposable liquid imparts a desired viscosity to the ink composition and which evaporates at a sintering temperature of the metal nanoparticle; an optional solvent; wherein the ink composition has a metal content of less than about 25 percent by weight, based upon the total weight of the ink composition; and wherein the ink composition has a viscosity of from about 50 to about 200 centipoise at a temperature of about 20 to about 30° C. A process for preparing the ink composition and for printing the ink composition. A flexographic printing process or gravure printing process including the ink composition.
While currently available conductive inks are suitable for their intended purposes, there remains a need for improved inks suitable for conductive ink applications. There further remains a need for alternative means for preparing inks that are low cost, easy to prepare, and have low post printing complexity. There further remains a need for such improved inks that are suitable as conductive inks for both two dimensional and three dimensional printing applications.
The appropriate components and process aspects of the each of the foregoing U. S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof. Further, throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.